It is proposed to examine the net ion movements induced in Halobacterium halobium envelope vesicles on illumination in the presence and in the absence of amino acids. An attempt will be made to establish the stoichiometric relationship between amino acid incorporation and H ion, Na ion K ion and Cl fluxes. The possible role of ATPase in the generation of a membrane potential in these vesicles will be examined, as will a similar role of metabolic enzymes still present in these membranes. Attempts will be made to isolate and characterize one or more carriers for amino acids from these vesicle preparations. The ion fluxes will be examined using radioisotopes, Na-22, K-42, and Cl-36. Uptake will be followed by trapping the vesicles on membrane filters and determining the radioactivity retained. The carrier will be enriched for on the assumption that the active molecule will specifically bind the amino acid or ion in question and follow the binding by equilibrium dialysis. The usual techniques of protein purification will be used, e.g., Sephadex gels, column chromatography, electrophoresis and ultracentrifugation.